The invention concerns a device for verifying, in particular for counting, preferably sheet-like articles, in particular printing products.
In the production of printing products, such as newspapers or periodicals for example, they are transported, for example, either lying individually or in the form of an imbricated stream on a conveyor belt, or respectively placed individually over saddles, from one processing station to the next. In this case, the number of products must be known as accurately as possible.
EP-A-0 408 490 discloses a device for counting printing products in which a contact element, which is arranged underneath an imbricated stream, is brought into contact with the trailing edge of a printing product. On contact with the trailing edge, a signal is emitted from a detector element, interacting with the contact element, to a counter.
The object of the invention is to provide a device of the type stated at the beginning which, while of as simple a construction as possible, permits reliable verification of the respective articles.
The solution achieving this object is provided by the provision of at least one feeler which can be acted on by articles moving in relation to the feeler in a verification region and can be moved from a stable feeling position into a stable evaluating position, a sensor for generating a verification signal when the feeler is in the evaluating position, and also a returning member for returning the feeler into the feeling position.
According to the invention, a bistable mechanical store is provided with which two different items of information can be stored, namely xe2x80x9carticle presentxe2x80x9d or xe2x80x9carticle not present.xe2x80x9d These two discrete states of the feeler are distinguished by the sensor, which is consequently able to read out the stored information. By means of the returning member, the feeler is, as it were, xe2x80x9cre-armed,xe2x80x9d i.e. transferred into its feeling position in which it can be acted on mechanically by an article to be verified. The feeler, according to the invention, may also be referred to as a toggle switch, which can be switched over by an article to be verified, or by the returning member, from one stable position via a dead center into the other stable position.
The device, according to the invention, is suitable, in particular, for counting printing products which are being transported, for example, lying in an imbricated stream on a conveyor belt. For this purpose, the device is brought up to the imbricated stream in such a way that the feeler or a contact element firmly connected to the feeler is located in a verification region lying in the path of movement of the printing products and is acted on by the leading or trailing edge of the moving product, for example a newspaper or periodical, and moved into the evaluating position. While the sensor generates a verification signal serving as a counting pulse, when the feeler is in the evaluating position, a counter connected to the sensor is not activated in the case of a missing product. Consequently, with appropriate coordination between on the one hand the expected setpoint time which elapses between the crossing of the verification region by two successive products and on the other hand the time which elapses from when the feeler is acted on until the point in time at which it is back in the feeling position in the verification region, all the products moved in relation to the verifying device can be counted or the absence of products actually expected can be detected.
Advantageous embodiments of the invention are specified in the dependent claims, the description and the drawings.
The invention is described below by way of example with reference to the drawings, in which:
FIG. 1a shows a side view of a verifying device having a plurality of feelers moving on a circular path for counting printing products according to one embodiment of the invention;
FIG. 1b shows a partially sectioned view of the device from FIG. 1a in a view turned through 90xc2x0 with respect to FIG. 1a; 
FIG. 2 shows another application of the verifying device from FIG. 1a; and
FIGS. 3a and 3b show schematic side views of a verifying device according to a further embodiment of the invention, with the feeler in the feeling position and in the evaluating position, respectively.